This invention relates to a process for manufacturing a hose having a reinforcement incorporated therein and an apparatus therefor, and more particularly to a process for manufacturing a hose comprising an inner tube and a reinforcement spirally wound on an outer periphery of the inner tube and an apparatus therefor.
Conventionally, there has been proposed a hose which exhibits flexibility and resistance to bending. The hose includes an inner tube made of a soft or flexible synthetic resin material and a reinforcement made of a hard or rigid synthetic resin material and spirally wound on the inner tube.
Such a conventional hose may be typically manufactured according to, for example, such a method as disclosed in Japanese Patent Publication No. 15218/1978.
The conventional method disclosed comprises the step of injecting a flexible synthetic resin material from a first injection head to form an inner tube. Then, the inner tube is fed to a first winding station, where a wire winding step of spirally winding a wire made of polyamide on an outer periphery of the inner tube is practiced. The wire winding step is carried out while keeping a flexible core rod inserted into the inner tube as extruded from an extruder or applying a pressure of compressed air to an interior of the inner tube, to thereby prevent the inner tube from collapsing.
The inner tube on which the spiral polyamide wire is thus wound is then provided with a reinforcement in the next step. More particularly, the reinforcement is wound thereon with a strip made of a rigid polyvinyl chloride material and then corrugatedly fitted between turns of the spiral wire through the strip.
The conventional hose which is manufactured through the above-described steps continuously taking place is subsequently passed through a heated conduit to carrying out welding of the reinforcement and the like. Then, the hose is provided thereon with an outer tube by means of a second injection head, followed by being cooled at a cooling station, resulting in the method being completed.
Also, it is generally required that such a hose is formed into accurate dimensions in association with a connection element to which the hose is to be connected. However, when such a hose is to be formed of a flexible synthetic resin material into an increased diameter, it is highly difficult to provide the hose with stable and precise dimensions. In order to solve such a problem, techniques of spirally winding a melted strip-like flexible synthetic resin material on a core rod are employed. In this instance, an increase in manufacturing speed is carried out by rotating the core rod to continuously feed the core rod with the strip-like resin material.
However, rotation of the core rod causes the hose formed on the core rod and then separated therefrom to be still rotated. In this instance, rotation of the hose is obliged to be continued until it is cut into a length for desired applications. Therefore, manufacturing of the hose must be carried out while cooling it with water and floating it on the water.
In the first conventional hose manufacturing method disclosed in Japanese Patent Publication No. 15218/1978, as described above, the spiral wire is wound on the outside of the inner tube. For this purpose, a winding machine is arranged at the first winding station. Unfortunately, this causes a whole hose manufacturing apparatus to be complicated in structure and large-sized, leading to an increase in manufacturing cost.
Also, in the first conventional method disclosed in the Japanese publication, the step of forming the inner tube is carried out separate from the step of winding the reinforcement on the inner tube formed, resulting in the manufacturing being deteriorated in efficiency and productivity.
In the second conventional method described above wherein the strip-like synthetic resin material is wound on the core rod, it is required to arrange a water tank having a length corresponding to that of the hose cut for desired applications. Unfortunately, this leads to large-sizing of the hose manufacturing apparatus. Also, the method causes rotation of the hose formed to be forcibly continued until it is cut into a required length for desired applications, so that it is substantially impossible to carry out an operation of winding the manufactured hose on a bobbin or subjecting the hose to marking.
In addition, the second conventional method causes level different regions to occur on overlap portions of the strip-like synthetic resign material of the hose thus manufactured. The hose is often coated on an inner surface thereof with a special coating depending on the applications. Unfortunately, such level different regions fail to permit the coating to be satisfactorily formed on the regions.
Further, the level different regions each exhibit resistance to flowing of fluid in the hose, resulting in flowability of the fluid being deteriorated. Moreover, the level different regions are often worn, so that a synthetic resin material which forms the level different regions is mixed with the fluid, leading to contamination of the fluid.